The subject matter disclosed herein relates to the art of measuring and monitoring axial vibrations to identify misalignments in turbomachinary trains.
Turbomachinary trains comprise a set of components having serially coupled rotating shafts. A common example is a turbogenerator, which in its simplest form includes a turbine having a rotating shaft (i.e., a rotor) directly connected to a rotating shaft of an electric generator for the generation of electric power. More complex turbogenerator trains, such as those utilized in the power generation field, often comprise several large components having rotating shafts coupled in series. For example, a typical configuration may include a high pressure turbine having a rotating shaft that is coupled to a rotating shaft of a low pressure turbine, which is in turn coupled to a rotating shaft of a generator.
When implementing such a train, it is imperative that the rotating shafts from each component behave in a precise manner in order to avoid damage the rotors or bearings. For instance, one common problem in such a configuration involves an unbalanced shaft, in which one of the shafts “wobbles.” This defect is commonly detected by measuring radial (i.e., outwardly directed) vibrations using e.g., piezoelectric probes. However, such vibrations may also result from misaligned shafts, which can also cause damage to the rotors or bearing.